The three most important design elements of digital printing

Because people can easily create effects such as color mixing, ghosting, and gradients in drawing and typesetting software, they have been used in a large number of applications, and one example of this is color misconfiguration that we can see in many publications.

When they are displayed on the screen, it looks very normal - other elements are as well. However, due to the limitation of resolution, digital presses are more suitable for printing ribbon-type originals.

If you want to use virtual light as a raster image, then opening this image in Photoshop can reduce blockiness to some extent (blocking, refers to a distinct color difference, not a color or ladder effect The smooth transition relationship.) The appearance of the phenomenon, in addition, you can also choose "add noise" filter, which is also our most common solution.

1. Learn how to calculate whether a given tone map will appear to be fragmented during copying.

2. Calculate the number of tones (or grayscale) that can be created by dividing the output resolution of a device by the number of screens in the device.

3. Use the above values ​​to calculate the actual number of colors within a given gradation range.

If the size of each ribbon is 0.05 inch/0.12 cm, or even less, the difference between the different ribbons is not so obvious and a smooth transition can be basically formed.

For example, on a screen with a resolution of 600 dpi and 85 screens, you can get 49 gray levels (N=600/85). If the gradient patches transition from 20% to 75% of one color, the decimal difference between them is 26.95 ((49)x(0.75–0.20)). If the length of this gradient patch is 5 inches, then the width of each ribbon is 0.18 (5/26.95) inches - the striping of the image will be very noticeable.

Suggestion: Although this is not a constant formula, it is very useful to you. If you get a ribbon size less than 0.05 inches, you can get a very perfect image. At present, most digital printers use the second-generation stochastic screening technology, which can greatly reduce people's computing work. But no matter what the situation, checking the problem by printing proofs is a safer way.

Toner coverage

Under normal circumstances, the total coverage of toner in a given area on a single sheet of paper will not exceed 320%, which means that the total toner coverage after printing four primary colors cannot exceed 320%.

From a technical point of view, we can achieve 100% coverage for each primary color toner, but the resulting printing results will be very unsatisfactory.

Suggest:

1, according to the toner coverage limit, you can create a new CMYK setting parameters in Photoshop, and the "Toner Total Coverage" maximum value is set to 320%.

In addition, you can reduce the dot gain by about 10% by using this default setting. Of course, maybe you can also reduce the dot gain to a lower level, but you must test each image to ensure that the printer you are about to use will not exhibit optical gain.

2. If you use the default SWOP parameters in Photoshop's CMYK settings, then your image will look less impactful than it was originally, but unfortunately, most designers and printers are not the default settings. Never use other filming. We should take the time to experiment with other parameters and keep in touch with the printing plant—even the equipment manufacturer—to find the best value.

Dot expansion

Dot enlargement (sometimes called the increase in tone value) is a common problem on lithographic printing presses, and it is caused by many factors - the spread of ink on paper, the expansion of dots in the traditional imaging process of printing plates, and Excessive printing pressure.

Of course, toner printers do not suffer from these problems, but dry toners are easily dispersed. After the liquid toner is spread on the rollers before being transferred to the paper, dot gain of digital prints is much lighter than that of offset printing products.

Suggestion: Consult your printing service provider to see if you need to adjust dot gain and toner coverage when converting images from RGB to CMYK. Keep in mind that when you create images in drawing and typesetting software, you should consider the problem of toner coverage.

Paper and paper orientation

The direction of the paper web depends mainly on the manufacturing process of the paper. Because the pulp moves with the conveyor belt of the paper machine, most of the paper fibers are aligned with the direction of the conveyor belt, which also forms what we call the direction of the strands.

Folding: When we fold an ordinary card or business card, we can easily see the importance of the direction of the paper.

Through observation, we can find that the creases that are perpendicular to the direction of the silkworm look rough, while the creases that match the direction of the silkworm look flatter. Folding the jobs along the silk direction is a goal that the printing factory has always pursued, but sometimes they will also give up this idea because cutting jobs along the wire may cause a lot of waste or increase the number of jobs. The difficulty of processing.

Recommendation: If it is necessary to fold the work piece against the direction of the wire, then it is necessary to ensure that the printing house uses high-quality paper. Only in this way can rough edges be avoided.

Pages printed on printers that use dry toner may also show creases in creases. Press creases can help avoid this problem, but the best solution is to consider folding in the design process. Problem, avoid using a lot of ink in places that need to be folded.

Paper swelling

Another problem related to the direction of the paper strands is its surprising hydrophilicity. As the humidity of the air increases, the paper fibers also expand, and its size can increase up to four times or five times.

If you bind books in a dry environment against the direction of the paper's silk, then when we put these books in a normal-humidity environment, their pages will be distorted, and the bound edges will change - This kind of book gives people a very bad feeling because its binding effect is really bad.

This is also a big problem for dry toner printers, because the fusion process of toner powder will release huge amounts of heat, which will take away a lot of moisture from the paper. The same problem exists in thermosetting web printers. .

Paper is a hydrophilic material and will begin to absorb moisture as soon as it is heated and dried.

Thermosetting web presses can reduce the temperature of the paper through the chill roll and promote the moisture absorption of the paper. In addition, many printers use additional rehydration units to supplement the water lost from the drying process.

We can also replenish their moisture by placing the printed paper in a sufficiently humid environment. If the dried paper has not been humidified within 72 hours, then the damage they suffer is permanent.

Recommendation: Select a printing plant that can provide good control of the humidity and temperature of the printing shop.

If you understand how to deal with these issues, you can design excellent digital prints.